Changes in heparan sulfate pattern but not in oncogene expression correlate with tumor growth in spontaneous transformation of cells.

For the clonal analysis of spontaneous malignant transformation of cells, a clonal cell line of low tumorigenicity, derived from a mouse embryo mass culture, was injected into syngeneic animals in a sufficient dose (10(7) cells) to produce tumors. Cell lines and clones produced from several such tumors had acquired a 10(4)- to 10(5)-fold higher level of tumorigenicity. Anchorage-independent growth did not co-select with tumorigenicity. There was no evidence for overexpression of proto-oncogenes in the highly tumorigenic clones; p53 protein and mRNA levels were also essentially equal and low. There was a specific structural difference in the O-sulfate residues in oligosaccharides of heparan sulfates in all the tumor cell lines when compared with their parent clone, similar to that observed before in SV40 virus-induced cell transformation (Winterbourne and Mora, 1978).